1. Technical Field
The present disclosure relates to a supply voltage removal detecting circuit and a display device having the same, and more particularly, to a display device that can promptly remove a latent image displayed on a panel when a battery is disconnected from the display device whose gate drivers cannot be concurrently turned on, and a method thereof.
2. Discussion of the Related Art
In passive matrix type display devices, when a supply voltage is disconnected, a driving voltage for a panel is discharged using a discharging circuit to remove a latent image displayed on the panel. In other words, when a battery is disconnected, the driving voltage applied to the panel is discharged to remove the latent image displayed on the panel.
The driving voltages for driving the panel that are discharged when the battery is disconnected include driving voltages to control the gate lines of the panel, and the driving voltage output by a source driver. The supply power is boosted to generate the driving voltage to control one of the gate lines and the driving voltage output from the source driver, and dropped to generate the negative driving voltage to control the other one of the gate lines.
In this case, a negative voltage is used to turn off the gate lines of the panel. If the negative voltage VGOFF changes from a negative voltage to a ground voltage due to the discharge, the gate lines of the panel allow a constant current to flow even though they are not completely turned on.
In this state, if the output voltage of the source driver is discharged to the ground voltage, the electric charge stored in a capacitor of the panel is discharged. As a result, the latent image displayed on the panel is removed, and a black and white image is displayed on the panel according to the panel properties.
Unlike passive matrix type display devices, in active matrix type display devices, for example, TFT-LCDs, when the battery for generating the supply voltage is disconnected, the latent image is displayed on the panel for a specific time, and then slowly disappears from the panel.
Thus, since active matrix type display devices do not discharge the driving voltages, the latent image is not removed promptly from the panel when the battery is disconnected.